Manipulating macronutrient intakes has no effect on body mass (weight) independent of energy balance. You lose weight on a diet, any diet, because your energy intake is less than your energy output (negative energy balance). If your weight loss has stalled you are now in energy balance so in order to continue losing weight you will have to either reduce your calorie intake further or increase your energy output until you are once more in a state of negative energy balance.

Makes complete sense however I am worried about going even lower than 1600 calories per day. Training is Starr's 5x5 (3x weekly), CF 2x weekly, and BJJ 1x weekly. Would going under 1600 calories a day not be harmful?